Push-button type fluid logic element for fluid control,indicating or recording system



United States Patent [72] Inventor Hikaru Hasegawa I-Iitachi-shi, Japan [21] Appl. No. 773,909 [22] Filed Nov. 6,1968 [45] Patented Dec. 29, 1970 [73] Assignee Hitachi, Ltd. Tokyo, Japan a corporation of Japan [32] Priority Nov. 6, 1967 [33] Japan [31] No. 42/71002 [54] PUSH-BUTTON TYPE FLUID LOGIC ELEMENT FOR FLUID CONTROL, INDICATING OR RECORDING SYSTEM 9 Claims, 18 Drawing Figs.

[52] US. Cl ..137/596.15, 235/200, 137/625.6 [51] 1nt.Cl ...F16k 11/00, 606d H02 [50] Field of Search 137/84- [56] References Cited UNITED STATES PATENTS 2,804,877 137/86X 9/1957 Rosenberger Primary Examiner-Henry T. Klinksiek AttorneyCraig, Antonelli, Stewart & I-Iill ABSTRACT: Fluid logical element comprising first and second chambers airtightly separated from each other by a flexible member, means having a portion for restricting the passage area of fluid flow and connecting the first and the second chambers with each other, valve means having one end connected with said flexible member, the other end of said valve means being connected with a member provided in the first chamber for opening and closing the fluid passage, operating means for said valve means and said flexible member provided at the side opposite to said flexible member, and fluid flow means provided in each of the first and the second chambers, the force applied by said operating means being effective to deflect said flexible member so that a portion of the fluid within said first chamber is exhausted through said fluid flow means, the other portion of the fluid within said first chamber being caused to flow into the second chamber through said connecting means.

PATENTEDBEEZQIBYB I 3550.620

sum 1 0F 3 INVENTOR HIKRRU HRSEGHAJH 6m} R/QJM' ATTORNIEKS PUSH-BUTTON TYPE FLUID LOGIC ELEMENT FOR FLUID CONTROL, INDICATING OR RECORDING SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention In order that the invention may readily be understood, a specific example in which the fluid logic element is utilized will now be described.

In a conventional process plant instrumentation system, a plurality of variables in a process such as pressure, flow rate, or temperature are transformed, by means of pneumatic transducers, to standardized'pneumatic signals of a predetermined range, and each of the signals is reconded by utilizing pneumatic recorder corresponding to each signal. However, as a tendency in a recent process plant instrumentation, a central control system in which a plurality of control instruments are gathered at a single place is employed,and the process variables are indicated and controlled at a remote place. At the same time, if necessary, a desired variable is introduced into and recorded on atrend recorder. The present invention is usable for such a purpose, i.e., as a fluid logic element access relay for taking out a desired one among a plurality of measured variable.

Further, as an example in which the present invention may be used for controlling a desired system among several systems to be controlled,,a bank of valves which are located at an inaccessible place such as a remote place, a narrow place or a dangerous place may alternately be opened and closed so as to allow or prevent fluid flow. In this case, the invention operates with the intervention of a fluid.

, The fluid logic element in accordance with the present invention has various applications.

Further, the fluid logic element in accordance with the present invention can effectively be used in a sequence control means for a fluid control system or in various relation and indication means.

Summarizing, the present invention has an object to provide a pushbutton type fluid logic element which is usable, in a fluid control, indicating or recording system, for selectively controlling, indicating or recording without being limited by the number of variables or the number of systems being controlled, and which is reliable in operation, easy to handle, simple to manufacture and has less air leakage.

2. Description of the Prior Art I-Iithertofore, as a means for taking out a desired measured variable, a mechanical selector valve and a pneumatic jack board means have been known, however, these means necessarily include slidable parts and are often accompanied with troubles caused by wear of'such parts and remarkable pressure leakage caused thereby.

Further, in the field for controlling a desired system among systems to be controlled, no such means has been previously known that uses a fluid logic element in accordance with the present invention.

SUMMARY or THE INVENTION In accordance with the access relay as a specific example to which a fluid logic element of the present invention is applied and by which a new measured variable is accessed and at the same time previously accessed variables are automatically canceled so as to be substituted by the new one, the disadvantages of the previously known mechanical selector valve or the pneumatic jack board can be overcome. In this respect, in order to simplify the manufacturing process, the present invention is embodied in a relay-type measured variable accessing means having a pushbutton and employ a molding method for manufacturing the same.

The characteristics required in a pushbutton type relay are as follows:

I. Once a pushbutton is depressed, it should be maintained in a condition in whichthe pushbutton is depressed even after the hand is relea, ed. In other words, an accessing operation should be continued.

2. When a new pushbutton among a pushbutton group is depressed, the previously depressed button should be returned to the original position so that the latter is substituted by the newly depressed one.

3. By returning all of the buttons to the initial position. such a condition in which no accessing is performed should be maintained.

The present invention-satisfies these requirements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic sectional view showing the structure of an access relay embodying the present invention;

FIGS. 2(I), (II) and (Ill) show the principle of relay actuation and operation in accordance with the present invention;

FIGS. 3(A), (B) and (C) show the relations among the access relay in accordance with the present invention. a communication and blocking relay and recorder;

FIG. 4 is a sectional view of the communication and blocking relay taken along line A-A of FIG. 5;

FIG. 5 is a plan view of the communication and blocking relay;

FIG. 6 is a sectional view of a further embodiment of access relay;

FIG. 7 is a cross-sectional view showing an example of the air passage which may be used in the access relay;

FIGS. 8(A) and (B) are each a cross-sectional view showing a further example of the air passage in the access relay;

, FIGS. 9(A) and (B) are each a cross-sectional view showing an O-ring valve seat of the access relay;

FIG. 10 is a cross-sectional view showing a further example of the O-ring valve seat of the access relay;

FIGS. 11 and 12 show the structures of a further embodiment of the access relay.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 shows a portion corresponding to one of relays in accordance with the present invention. The illustrated relay comprises a base I which is constituted by opposed first and second chambers, a communication passage connecting said two chambers, and passage communicating with these chambers. The first chamber is formed with a supply chamber 8 having an inlet port 16 for the supply pressure Ps, and the second chamber has a flexible membrane 4 which separates the chamber into inner and outer chambers 2 and 3 respectively. The chambers 8 and 2 are connected with each other by a communication passage 7. The communication passage 7 has a branch passage I0 provided at the intermediate portion thereof, the branch passage 10 being led to the chamber 3 through a restricted portion 11. The chamber 2 has a communication port 14 for connecting-the chamber with corresponding portions of other relays. The chamber 3 is provided with an output port 15 and an exhaust port 13. The exhaust port 13 defines a valve seat 13' by the periphery of its opening. A pair of opposed valves 5 and 6 are provided and connected with each other by means of a rod passing through the communication passage 7. The valve 6 is urged toward the second chamber by means of a spring 9 so as to seat on the valve seat 7 The valve 5 is secured at its end to the flexible membrane 4 and normally maintained apart from the valve seat 7 Further, the flexible membrane 4 has a connecting rod I2 projecting from the center thereof and passing through the exhaust port 13 so as to form a pushbutton 12 by its extreme end. The pushbutton is so formed that its one end face sealingly engages with the valve seat 13' provided at the opening of the exhaust port 13.

The operation of the fluid logic element in accordance with the present invention will now be described with respect to an example in which a plurality of such elements are connected.

First of all, as shown in FIG. 2(I), the supply pressure Ps is introduced into the elements, and thereafter the pushbutton 12 is depressed to close the exhaust port 13 and movethe valve 5 into sealing engagement with the seat 7". At the same time, the valve 6 is moved apart from the seat 7 in the other relays b and c, the valves 6 are maintained in sealing engagement with the corresponding seat 7' by means of the springs 9 and the exhaust ports 13 are opened to the atmosphere. Since the pressure Ps within the relay a is introduced through the passage 10 and the restricted portion 11 into the chamber3, the pressure within the chamber 3 is caused to increase. As the result, the pressure within the chamber serves to force the flexible membrane 4 upwardly so as to maintain the valve 5 in the sealing engagement with the seat 7". Therefore, even when the depressing force applied to the pushbutton is released, the pushbutton is maintained in the depressed position. Thus, the first requirement. for a pushbutton-type relay is satisfied and the supply pressure Ps is accessed through the output port 15. I

r Then, as shown'in FIG. 2(ll), when the push button of the relay b is depressed, the valve 6 of the relay b is moved apart from its seat- 7 and thesupply pressure Ps is rapidly introduced through the communication passage 7 and the passages 14 into the chambers 2 of the relays a and c At the same time, a portion-of the pressure Ps is allowed to pass through the passages 10 of the relays b and c and exhausted through the exhaust.port l3, however, the amount of the exhausted pressure is small as compared with the ,input flow due to the existence of the restricted portions 11. Therefore, the

pressure within the chamber 2 of the relay a increases to such an amount thatthe pressure at the opposite sides of the flexible membrane 4 of the relay a is equalized. Thus, the pushbutton 12 .of the relay a isdownwardly moved under the influence of the spring 9 with the result that the exhaust port 13 of the relay a is opened and the air within the chamber 3 is rapidly exhausted through the exhaust port 13. In the relay c, the flexible membrane 4 only receives a force to urge it downwardly, so that the position of the relay is remained unchanged. After this condition is achieved, if the pushbutton 12 of the relay b is further depressed so as to simultaneously close the exhaust port 13 and the seat 7" by the pushbutton 12 and the valve 5 According to the present invention, the relay is simple in construction, satisfies all of the three requirements for a pushbutton-type relay, reliable in operationanrleconomical'in that it has no air consumption except during a transient period.

The output P0 of the relay in accordance with the present invention can be used to positively access .a process variable Pmij by the recording portion A by connecting'a communicating and blocking relay as shown in H0. 3C.

For the purpose of the explanation, the communication and blocking relay will now be described.

FIG. 4 shows a pneumatic access relay in the form of a diaphragm-type composite logical element which may be used as a communication and blocking relay.

In recent process plant instrumentation, a plurality of longitudinal type indication and control'instruments are often gathered at a single place to control each of the measured.

variables, a desired variable being accessed by and recorded:

on a separate trend recorder. r

In this respect, in order to access each of-the measured variables, a valve having sliding parts has been used for selectively connecting a port leading to the air pressure corresponding to the variable with a port leading to the recording means.

' Generally, the ,requirernentsfor this selecting operation will be respectively, the pressure within the chamber 3 of the relay b is caused to increase under the influence of the pressure Ps transmitted through the passage 10, so that the flexible membrane 4 .is pushed upwardly closing the communication passage 7. Thus, the air within the chambers 2 of the relays a, band c are exhausted through the communication passages 14, the passages 10 of the relays a and c, and the exhaust port 13 of the relays a and c.- In this manner, the pressure in the chambers-2 of the relays a, 'b and c is decreased as low as the atmospheric pressure. Thus, the flexible membrane 4 of the relay b. is subjected to the pressure only at the side of the chamber 3 so as to urge the valve 5 toward the seat 7". Therefore, even when the depressing force applied to the pushbutton 12.of.the relay bis released, the relay is maintained in the position shown in FIG. 2(lll), and the signal pressure corresponding to a desired variable is accessed through the output port 15. Thus, the arrangement satisfies the second requirement as well as the first one.

Suppose that, in the position .as shown in FIG. 2(111), the pushbntton of the relay b is pulled against the force acting on the flexible membrane 4. Then, the pushbutton 12 and the valve 5 of the same relay is moved from the seats 13' and 7" respectively, and the air within the chamber 3 is exhausted through the exhaust port 13. At the same time, although the pressure Ps is distributed to the chambers 2 of the relays a, b and c, the relays a andb are maintained in their original position,-..whilein the relay b, the pushbutton 12 is further depressed downwardly due to the pressure acting on the flexible membrane .4and the force of the spring 9 until the valve 6 sealingly engages with the seat .7 to close the communication passage 7. In this manner, the pressure within the chamber 3 of the relays a, b and c becomes to be equal to the atmospheric pressure. Thus, the arrangement satisfies the above described third renuirement for a pushbutton-tyne relay.

summarizedasfollowsi 1. The air pressure corresponding to the measured variable should not leak to the outside.

2. The air pressure representing the variables other than that to beaccessed should be separated from the record? ing means. r r

3. When the air pressure representing a new variable to be measured is being accessed-the previously accessed air pressure should necessarily be exhausted and blocked from the interior of the recorder. i

However, according to the prior valve system, since it includes sliding parts, the air pressure representing a measured variable is apt to leak through the sliding portions, so th'ata highly precise machining is required in order to overcome the" problem of leakage. This results in increase in manufacturing cost as well as a tight and sticky operation of the valve. Moreover, a simple selection of ports will not be sufficient to meet the above listed requirements 2 and 3.

The present invention overcomes the above described disadvantages of a previously known pneumatic-type access relay, and has an object to provide such a relay that not only satisfactorily meets the above described requirements 1 2 and 3 but also is easy to operate, simple to manufacture and lower in cost.

The present invention will now be described in detail with reference to the accompanying drawings. FIG. 4 is a sectional view of. a portion corresponding to a pneumatic-type access relay in accordance with thepresent invention. In this figure, the numerals 31, 32 and 33 respectively designate an intermediate plate, an upper closure plate and a lower closure plate, each of which has flow passages and diaphragm cavities and is made of plastic material and the like by, for example, a molding method. Flexible membrane such as cloth-based rubber plates 34 and 35 are respectively secured between the plates 31 and 32 and between the plates 32 and 33. Each of the flexible membranes 34 and 35 serves as a diaphragm at each of the diaphragm cavities and as a packing seal at the other portions. The plate 31 is provided with oppositely disposed diaphragm cavities 36 and 18, and 22 and 21 respec tively on the upper and lower surfaces. The cavities 36 and 18, and 22 and 21 are connected by fluid ports 37 and 39 respectively. Each end of the ports 37 and 39 defines a nozzle opening 24, 27, 22 or 48. Rods 38 and 40 pass through the ports 37 and 39 respectively and have the ends connected to the support plates 25, 26, 23' and 20 which are in turn secured to the membrane 34 or 35. The support plates may be omitted.

Further, the upper closure plate 32 has a diaphragm cavity 17 provided at the position oppositeto the diaphragm cavity 36 with the intervention of the membrane 34. The plate 32 also has a hole 43 leading from the cavity 17 to the source of a measured variable Pmij. in this cavity, a spring 45 is disposed so as to urge the support plate 25 into sealing engagement with the nozzle 24. The spring 45 may be omitted if the membrane 34 is made of a resilient material. The membrane 34 is provided with a hole 25' for connecting the diaphragm cavities l7 and 36 with each other. The plate 32 also has a diaphragm cavity 23 provided at the position opposite to the diaphragm cavity 22 in the intermediate plate 31, the cavity 23 opening to the atmosphere through'a hole 47. A spring 46 is provided in the cavity 23 for urging the support plate 23' into sealing engagement with the nozzle 22' As in the case of the spring 45, the spring 46 may be omitted.

The lower closure plate 33 has a diaphragm cavity 19 provided at the position opposite to the cavity 18 in the intermediate plate 31 with the intervention of the membrane 35. In the cavity 19, the signal pressure p.s.i.g. is introduced through a hole 42. The plate 33 also has a diaphragm cavity 20 at the position opposite to the diaphragm cavity 21 with the intervention of the membrane 35. The diaphragm cavities 19 and 20 are connected with each other by means of a passage 41 having a restricted portion 29.

The diaphragm cavity 36, the membrane 34, and the diaphragm 17 are so arranged that they constitute the chamber 1. The chamber may not necessarily be formed by the aforementioned upper, intermediate and lower plates, but it may be formed as aunitary construction by a casing including the diaphragm cavities 36 and 17. This may also be applicable to the other chambers 1'. 2 and 2'.

According to the present'invention having the construction as described above, the measured variable Pmij is introduced through the hole 43 into the diaphragm cavity 17, and then through the hole 25 into the diaphragm cavity 36. However, due to the sealing engagement between the support plate 25 and the nozzle 24 under the influence of the spring 45, the variable is prevented from entering the port 37, the passage 28 and the diaphragm cavity 18. Further, since the diaphragm cavity 18 is open to the exhaust passage 30, the atmospheric pressure prevails in the port v37, the passage 28 and the diaphragm cavity 18. In this condition, since the support plate 23 and the nozzle 22' re maintained in sealing engagement under the resilient action of the spring 46, the port 39 and the portions which are located downstream side thereof are separated from the'diaphragm cavity 22. p

In this condition, when the signal p.s.i.g. is introduced through the hole 42, the portion of the membrane located within the diaphragm cavity 19 serves as a diaphragm compressing the spring 45 so as to. force the support plate 26 into sealing engagement with the nozzle 27. Thus, the port 37 is cut from the communication with the exhaust passage 30, and at the same time, the support plate 25 is moved apart from the nozzle 24 to allow the measured variable Pmij pass through the port 37 and the passage 28 into the diaphragm cavity 22. The measured variable Pmij acts on .the'portion of the membrane 34 which is located in the diaphragm cavity 22 so as to move the support plate 23 apart from the nozzle 22. The signal pressure p.s.i.g. introduced through the passage 41 and the restricted portion 29'into the diaphragm cavity 20.acts on the membrane 35 and force the rod upwardly so as to further increase the gap between the support plate 23' and the nozzle 22'. Thus, the pressure corresponding to the measured variable Pmij is transmitted from the port 39 through the passage 44 to the recording portion Prec so as to record the variable.

When the signal pressure p.s.i.g. is vanished, the rod 38 is moved downwardly under the influence of the spring 45 and the nozzle 24 is closed to block the port 37 and the diaphragm cavity 36 from each other, n'cl at the same time, the nozzle 27 is opened into communi'ca ion through the diaphragm cavity 18 with the atmosphere. T us, the air within the recorder is exhausted to the atmosphe e through the port 39, the passage 28 and the port 38, however, exhausting of the signal pressure within the chamber 20 is delayed due to the existence of the restricted portion 29, so that the pressure holds therod'40 in its raised position for a certain period to keep the nozzle in the open position. After the air within the recorder is completely exhausted, the signal pressure p.s.i.g. is also completely exhausted through the restricted portion 29 and the plate 23' is forced into sealing engagement with the nozzle 22' so as to close the interior of the recorder from the atmosphere. Thus, the above described requirement 3 is satisfied.

The pneumatic-type access relays in accordance with the present invention are provided, as shown in FIG. 5, one for each variable. When the air pressure corresponding to the variable Pmij is not to be accessed but that corresponding to the variable Pmij' is to be accessed, the air pressure Pmij is introduced from the recorder through the passage 44 into the port 39 of the relay for the variable Pmij. lit this instance, since the nozzle 22 is closed, the portion of the membrane 35 which is located in the diaphragm cavity 21 is subjected to the pressure Pmij'. so that the rod 40 is further forced downwardly to assist the sealing contact between the plate 23" and the nozzle 22'. Thus, the above mentioned requirement 2 is completely met, and since the relay is of complete airtight construction, the requirement 1 is also met.

Further, as shown in FIG. 5, the arrangement is readily applied to an apparatus for measuring a plurality of variables. in this figure, the passages and the diaphragm cavities are formed in a single plate and the upper, intermediate and lower plates are simply assembled with a membrane interposed between each pair of the plates. Thus, a plurality of relays are constructed in a very compact and simple form at a lower cost without including any complicated movable portions. Further, according to the relay of the present invention, the access command is given in the form of an air pressure, so that, in

contrast with a conventional sliding type relay, it can be remotely controlled.

Referring again to HQ 3, descriptions will be made with respect to an example in which an access relay in accordance with the present invention is combined with a communication and blocking relay for recording a measured variable. The output Po from the pushbutton-type relay is introduced through the passage 15 into the second relay chamber 19 and 20. In this instance, the output P0 is introduced into the chamber 20 through the restricted portion 29. Therefore, pressure acts at first on the flexible membrane 26 and with a certain delay on the flexible membrane 20' so as to close the valve 27 and open the valves 24 and 22'.

The measured variable Pmij is introduced from the chamber 17 through the hole 25 the valveportion 24 and the passage 28 into the valve portion 22. and thereafter through the passage 31 into the recording portion. 1

When the pressure in the output port 15 of the pushbuttontype relay is exhausted through the exhaust port 13, the valve 24 of the communication and blocking relay is closed and the valve 27 is opened'so as to exhaust thepressure within the recorder through the passage 30. At this moment, the rate of decrease in pressure within the chamber 20 is low due to the existence of the restricted portion 29. Therefore, the valve 22' is closed only after the pressure in the recorder is completely exhausted.

The base plate of the pushbutton-type relay in accordance with the present invention includes only two opposed chambers and air passages, so that it may readily be manufactured by molding of plastics and the like. Further, accordingly to the present invention, a plurality of relays are very easily produced in a compact form. Therefore, a plurality of relays corresponding to a plurality of process variables can be gathered at a single place. Moreover, a desired process variable can be readily accessed by or canceled from the recording portion by a simple actuation of the pushbutton. Thus, the relay in accordance with the present invention is very effective as an access relay for a recording instrument.

; In the above described pushbutton-type access relay, since any improper engagement between the valve and the valve seat will cause erroneous operation, a guide may possibly be provided in the valve port, however, in such an arrangement, the flow resistance of the valve will be adversely effected. Thus, an improvement of one of the required characters will spoil another character.

The present invention further has an object to provide an access relay for a recorder comprising a novel diaphragm-type fluid logic element in which above described disadvantages of a conventional fluid logic element with movable parts are overcome and which has a secure engagement between a valve and a valve seat as well as a good flow characteristic.

FIG. 6 shows a construction of such an access relay embodying the present invention. In this figure, corresponding parts are identified by the same numerals as in FIG. I.

This relay is characterized in that it has spline grooves in the air passages 7. According to the present invention, the section taken along the line A-A in FIG. 6 does not have a uniform gap as shown in FIG. 7, but is provided with splinelike grooves 70 in the air passage 7 connecting the opposed chambers 8 and 17 as well as in the exhaust air passage 7 extending from the chamber 3. By this arrangement, the air can be exhausted from the chamber 3 in a rapid and secure manner. Further, since valve connecting rods 12' are engaging with the inner surfaces of the air passage to be guided thereby, the positions of the valves 6, 18 and will not be adversely affected by external shock load or variation in the attitude of the relay. Thus, the secure engagement between the valve and the valve seat can be ensured and the movements of the valves 6, l8 and Sare restricted only in the longitudinal direction. In the example shown in FIG. 8, four spline grooves are provided, however, the number of the grooves may be varied as desired.

- As described above, according to the present invention, positive valve movements are ensured and the flow characteristic is improved. Moreover, the spline grooves can readily be formed by a known plastic molding method and the relay is well suited for mass production. Thus, the present invention is effective for achieving its objects. I

The connecting and blocking portion of the access relay described with reference to FIG. I normally comprises a valve and a valve seat with an O-ring. In locating the O-ring in the valve seat, various means are employed in order to prevent the O-ring from being disengaged from the seat when the valve is displaced. For example, asshown in FIG. 9a, the O-ring 47 may be bonded to the seat by using a suitable adhesive 50, or the valve seat may be provided with an annular groove 52 for receiving the O-ring.

However, the former method is disadvantageous in that the O-ring is hardened due to the action of the adhesive 50and lose its resiliency. In the latter method, since the O-ring is received in the groove with somewhat compressed condition, its resiliency will also be decreased. As the result, a slight displacement of the valve will create a gap to cause air leakage. Thus, the above described methods willnot be effective to ensure a positive operation. According to the present invention, these problems can be effectively solved. The resiliency of the O-ring is not adversely affected and the O-ring is held on the seat so that it will not be displaced even when it is moved to engage with the valve. Thus, a slight movement of the valve will not create any gap, and the relay can perform a positive movement without any air leakage.

"According to the present invention, as shown in FIG. 10, a projection 51 is provided above the O-ring seat in such a place that a slight vertical movement of the O-ring is permitted. Upon downward movement of the valve 18, the O-ring tends to jump due to its resilient nature and under the influence of the transient fluid pressure, however, it is prevented from a further upward movement by the projection 51. In this condition, as the valve 18 is gradually moved downwardly, the O- ring moves along the wall 50 of the O-ring seat and the inclined surface of the valve I8 serving to seal the fluid. Thus, m (Li-inn ic Minced tn mnve'and deformed in sequence as shown by the lines 49, 49 and 49" to perform a leak-proof positive operation.

Therefore, the advantages of the present invention can be summerized as follows:.

l. Resiliency of the O-ring is not lost.

2. Automatic blocking function is performed.

3. The O-ring is not disengaged from the seat.

4. Easy to assemble.

5. Slight eccentricity is permitted.

Further, the valve seat in accordance with the present invention can readily be made by a known plastic molding technique and is suitable for mass production. Thus, the arrangement is very effective for achieving the objects of the present invention.

Now, a method for producing the access relay shown in FIG. 1 by molding plastic material will be described. The access relay may be formed separately as stationary parts in the form of an upper closure plate, an intermediate plate and a lower closure plate designated by reference numerals 53, 54 and 55 respectively and having flow passages and diaphragms, and as movable parts in the form of valves and connecting rods.

The upper closure plate comprises a chamber 3, an exhaust port 13, an output port 15 and a valve seat 13'. and an O-ring 49 can be disposed on the valve seat 13. The intermediate plate has a chamber 2, a communication passage 7 and valve seats 7' and 7" integrally formed therewith. The lower closure plate has a chamber 8 and a communication port 14 integrally formed therewith. A packing 56 is disposed between the lower closure plate and the intermediate plate for sealing purpose. Next, the movable parts will be described. Since the valve6 is so arranged that it is constantly urged toward the chamber 2 by means of a spring 9 and opened by the connecting rod 12 the valve takes theform of a ball valve disposed between the chamber 8 in the lower closure plate and the valve seat 7 in the intermediate plate so as to facilitate installation of the valve. Further, since it is not desirable from manufacturing and sealing point of view to form the passage 10 and the restricted portion 11 shown in FIG. 1 through the upper and intermediate plates, they are formed in the connecting rod 12'. The flexible membrane 4 is disposed between the upper and intermediate plates across the connecting rod so as to separate the chambers 2 arid 3 from each other. By this arrangement, the relay can be assembled by simply superposing and securing together the molded lower closure plate 55, the spring 9, the packing 56, the ball valve 6, the intermediate plat 54, the connecting rod 12. the flexible membrane 4 and the upper closure plate 53. Thus, a multiple relay can be formed in a compact and simple manner with lower cost. Further, the relay thus constructed is reliable in operation.

The access relay system using a fluid logic element shown in FIG. 1 has the following three problems.

' l. A pushbutton is maintained in its retracted position once it is depressed, however, if the amount of retraction is small, it is difficult to visually know which one of pushbuttons is depressed.

2. By erroneous actuation, more than two pushbuttons may possibly be depressed.

3. When a measured variable is being accessed, if the supply pressure (Ps) is decreased to zero, the pushbutton will be returned to itsoriginal position, and it is not possible to continue recording of the measured variable.

According to a further embodiment of the present invention shown in FIG. 12, the above described problems can be effectively solved.

FIG. 12 is a side elevational view of an access relay made in accordance with the present invention, the details of the internal structure and the connection between the pushbutton-type relays, the transmitter and the recorder are not shown in the drawing.

A casing 57 containing the pushbutton-type relays is provided with pushbuttons 12 one for each measured variable. In front of the pushbuttons 12, there is disposed a pinboard 58 of friction material which has a plurality of pin holes 59 located opposite to pushbuttons 12.

A desired measured variable can be accessed by removing a previously inserted pin 60 and replacing it into the hole 59 corresponding to the variable to be accessed. Thus, by utilizing the pinboard 58 and a pin 60, the above mentioned problems 1 and 2 can be solved.

Unless the pinboard and the pin are not provided, when the supply pressure (Ps) is decreased to zero during accessing operation, the pressure introduced through the passage and the restricted portion 11 in FIG. 1 for urging the flexible membrane 4 will also be vanished, so that the pushbutton will be returned to the initial position under the influence of the spring 9. However, according to the present invention, even when the supply pressure is decreased after a pushbutton is depressed, the pin is frictionally held in its depressed position during the supply pressure is zero as well as during the supply pressure is recovered. Therefore, as soon as the supply pressure is recovered, the measured variable can be accessed by the recorder.

As described above, according to the present invention, the objects can be sufficiently achieved by simply providing an access relay which is additionally provided with a pinboard having pinholes located opposite to the pushbuttons and a pin.

adapted to be inserted into one of the pinholes in the pinboard and frictionally held thereby.

Thus, the access relay in accordance with the present invention completely satisfies the three requirements necessary for a pushbutton-type access relay, and can perform a perfect relay function. Moreover, according to the present invention, a multiple relay can be readily formed. Further, the present invention also provides a communication and blocking relay which can be used independently or in combination with other relays or with said access relay to fonn an accessing device. Still further, the present invention provides a pushbutton-type logic element which is effective for controlling or accessing one of the multiple control systems or measured variables.

Iclaim:

l. A fluid logic element comprising first and second chambers opposed with each other, a communication passage connecting said two chambers, a flexible member separating the second chamber into inner and outer part at the side opposing to said first chamber, a pair of valves connected with each other by means passing through said communication passage so as to alternately open and close said communication passage, said valves being urged toward the second chamber and connected at one end with said flexible member, said second chamber having an exhaust port in the outer part, a pushbutton passing through said exhaust port and attached to the central portion of said flexible member, for actuating said valves, a communication conduit registering to said communication passage and the outer part of said second chamber and having a restricted portion, an inlet port for introducing a supply pressure into said first chamber, a communication port provided in the inner part of said second chamber, and an output port provided in the outer part of the second chamber.

2. A combination of a pluralityof fluid logic elements as defined in claim 1, a common supply pressure is introduced into the inlet port of each element, the communication ports in the inner parts of said second chambers of the elements are connected with each other, the output of each element being taken out from the output port in the outer part of the second chamber of each element.

3. in combination, a fluid logic element as defined by claim 1, and a communication and blocking fluid logic element including first relay portion and the second relay portion, said first relay portion comprising two chambers opposed with each other, a port connecting said two chambers toegther, a flexible member provided in each of said chambers and separating the chamber into inner and outer parts along the opposed faces of the two chambers, a rod passing through said port and connecting the flexible members in said two chambers together, the port defining a nozzle at the point of communication with each of said two chambers, one of said chambers having in its outer part an inlet port for a measured variable signal, the outer part of the other of said two chambers having an inlet for an access signal and the inner part thereof having an inlet for an atmospheric pressure, said second relay portion comprising two chambers which are separated by flexible member as in the first relay portion, said members are connected with each other by a rod passing through a port having nozzle openings, one of said two chambers being provided at its outer part with an inlet for an atmospheric pressure, the port of said first relay portion being connected with the inner part of said one of the chambers in the second relay portions, the outer part of said other of said two chambers in the first relay portion being connected through a restricted portion with the outer part of said other chamber in the second relay portion, the port in the second relay portion being provided with a hole for taking out an output signal; a supply pressure being introduced into the supply pressure inlet port of the first chamber of the pushbutton-type access relay, the output port provided in the outer part of the second chamber being connected with the second chamber of the first relay portion of the communication and blocking relay the access signal introduced through the measured variable signal inlet port of the first chamber of the first relay portion being transmitted through the grooves in the port of the second relay portion.

4, A fluid logic element in accordance with claim 1, said first and second chambers being connected with each other through spline grooves.

5. A fluid logic element in accordance with claim 1, comprising valve seats for a pair of valves and a pushbutton, said buttons being connected with each other by means passing through the communication passage and adapted to alternately open and close the passage, said valves being further urged toward the second chamber by a resilient member, each of said valve seats having a projection disposed so as to permit a predetermined movement of the O-ring in the valve seat.

6. A fluid logic element in accordance with claim ll, the element comprising an upper closure plate integrally formed with the outer part of the second chamber, the exhaust port, the output port and the valve seat, an intermediate plate integrally formed with the inner part of the-second chamber, the communication passage and the valve seat, a lower closure plate integrally formed with the first chamber and the communication part, a valve 6 disposed in the lower and intermediate plates so as to cooperate with the valve seat, a spring for urging the valves toward the second chamber, a connecting rod integrally formed with a valve 5 and having a passage re and a restricted portion 11, a flexible member being provided between the upper closure plate, the intermediate plate and the connecting rod.

7. A fluid logic element in accordance with claim l, the element further comprising a pinboard disposed in front of pushbuttons and having pinholes corresponding to the pushbuttons, and a pin adapted to be inserted into the pinboard.

8. A fluid logic element including first relay portion comprising two chambers opposed with each other, a port connecting said two chambers together, a flexible member provided in each of said chambers and separating the chamber into inner and outer parts along the opposed faces of the two chambers, a rod passing through said port and connecting the flexible member in said two chambers together, the port defining a nozzle at the point of communication with each of said two chambers, one of said two chambers having in its outer part an inlet port for a measured variable signal, the outer part of the other of said two chambers having an inlet for an access signal and the inner part thereof having an inlet for an atmospheric pressure; and second relay portion comprising two chambers which are separated by flexible members as in the first relay portion, said members are connected with each other by a rod passing through a port having nozzle openings, one of said two chambers being provided at its outer part with an inlet for an atmospheric pressure; the port of said first relay portion being connected withthginner part of said one of the chambers in the second relay portion, the outer part of said other of said two chambers in the first relay portion being connected through a restricted portion with the outer part of said other chamber in the second relay portion, the port in the second relay portion being provided with a hole for taking out an output signal.

9. A fluid logic element in accordance with claim 8, said element comprising an upper closure plate integrally formed with the outer part of said one chamber of the first relay portion and the outer part of said one chamber of the second relay portion, an intermediate plate integrally formed with the inner parts of the two chambers of the first relay portion and the inner parts of the two chambers of the second relay portion, and a lower closure plate integrally formed with the outer part of said other chamber of the first relay portion and the outer part of said other chamber of the second relay portion, a flexible member being disposed between each pair of said plates. 

